Personal computers, car navigation equipment and audio equipment of recent years are often provided with a tray for allowing the entry and exit of a CD (Compact Disk) or a DVD (Digital Versatile Disk). The opening and closing of the tray are normally controlled by the drive of a load, such as a coil or motor including a rotor. There are proposals for various methods for load drive control; for example, Patent Document 1 discloses a technology in which a torque value to be supplied to a motor is controlled by detecting the speed and position of the motor and comparing the results of detection with target values.
[Patent Document 1]
Japanese Patent Application Laid-Open No. Hei05-328774.
Conventionally, there have been cases where an amplifier circuit for amplifying input voltage is used to supply drive voltage to a load, such as a motor. However, when a fault occurs in the amplifier circuit or in a circuit near it due to a certain factor, there have been cases where a sufficient drive voltage cannot be supplied to the load or, under certain circumstances, the function of the equipment is impaired. For example, when a short circuit occurs in the amplifier circuit or in a circuit near it, the drive voltage supplied to the load may become 0 V, and the tray may not be opened or closed. Therefore, it is preferable that even in an emergency, such as the occurrence of a fault, a certain voltage can be supplied as an act of necessity.